This invention relates to an optical disk apparatus equipped with a pick-up which is driven by a signal on which a high frequency signal is superposed, and more particularly to an optical disk apparatus in which unnecessary radiation leaking externally is attenuated by a radiation shielding section formed to cross over a disk read section equipped with the pick-up.
In a DVD reproduction apparatus, a pick-up is driven by a signal on which a high frequency signal at e.g. 350 MHz is superposed. This generates unnecessary radiation from the pick up. However, such unnecessary radiation is shielded by a front panel of an enclosure, where it is made of metal, so that the level of the unnecessary radiation leaking externally is attenuated.
On the other hand, where the front panel is made of resin in order to reduce cost of the apparatus, since no shield is located in front of the front face of the enclosure, the level of the unnecessary radiation leaking externally from the front side is enhanced. In order to prevent this, a configuration was proposed in which the entire rear surface of the front panel is covered with a metallic plate. However, the structure for attaching the metallic plate was made complicate since a switch and other components are provided on the front panel. Therefore, conventionally, a configuration was adopted in which the entire upper surface and side surfaces of a disk read section equipped with the pickup are covered with a metallic plate (first prior art).
Another configuration in which a magneto-optic disk apparatus is equipped with a contact is disclosed in the Unexamined Japanese Patent Application Publication No. Hei 11-203742. Specifically, in this technique, an electrode wire of carbon fiber with good conductivity is supported by a clamper on a supporting arm of a magnetic head. The rear end of the electrode wire is connected to a grounding level. Therefore, during a read operation, the electrode wire is brought into contact with the label face of the optical disk earlier than the magnetic head. Thus, static electricity is discharged from a charged optical disk so that the control circuit and audio circuit are protected from discharging electric shock. Deposition of dust on the optical disk is also prevented (second prior art).
However, where the first prior art is adopted, the following problem was presented. Specifically, where the upper surface and side surfaces of the disk read section equipped with the pickup are covered with a metallic plate, the pickup cannot be directly seen unless the metallic plate is removed. Therefore, when the state of the pickup must be checked, such as the case where maintenance is executed for the apparatus, the metallic plate must be removed. This increased the time and labor of maintenance.
Further, the second prior art, which intends to discharge the static electricity from the charged optical disk, was a technique difficult to use from the standpoint of preventing the unnecessary radiation.
This invention has been accomplished in order to solve the above problems. An object of the invention is to provide an optical disk apparatus which can attenuate unnecessary radiation at a high frequency without increasing the time and labor during maintenance even when an enclosure with a front panel of resin and the other sections of metal is used in such a manner that a radiation shielding section is provided in the vicinity of the front panel so as to cross over a disk read section equipped with a pickup.
Another object of the invention is to provide an optical disk apparatus which can increase the rate of attenuating the unnecessary radiation by providing a radiation shielding section with two shielding planes in parallel to the front panel.
Another object of the invention is to provide an optical disk apparatus which can increase the attenuation coefficient of the unnecessary radiation by arranging a contact member on the upper surface of radiation shielding section so to connect the radiation shielding section to a top table.
Still another object of the invention is to provide an optical disk apparatus which can increase the withstand voltage for static electricity by providing two contacts.
A further object of the invention is to provide an optical disk apparatus which can increase the strength of a front panel by securing the contact members to a horizontal section by screws through upper supporting members formed at the front panel.
In order to solve the above problems, this invention provides an optical disk apparatus provided with a pickup which is driven by a signal on which a high frequency signal is superposed, comprising: a radiation shielding section including a horizontal section in parallel to a bottom plate of an enclosure, and vertical sections which extend downwardly from both ends or the horizontal section, and provided in the vicinity of a front panel to cross over a disk read section equipped with the pickup, wherein each of the horizontal section and the vertical sections has first shielding planes in parallel to the front panel and a second shielding plane perpendicular to the front panel, and the vertical sections are secured to the bottom plate at their lower ends.
In such a configuration, a part of the unnecessary radiation generated toward the front panel from the pickup is attenuated by the first shielding planes and another part thereof is attenuated by the second shielding plane. The radiation shielding section does not cover the upper section of the disk read section.
In addition to the above configuration, the second shielding plane is rectangular, and the first shielding planes are provided on both ends in the width direction of the second shielding plane.
In this configuration, a part of the unnecessary radiation generated toward the front panel from the pickup is attenuated by the first shielding planes close to the disk read section and another part thereof is attenuated by the first shielding planes close to the front panel when they are brought into contact with the top plate.
In addition to the above configuration, the horizontal section is equipped with contact members for electrically connecting the top plate to the radiation shielding section.
Namely, the horizontal section of the radiation shielding section is electrically connected to the top plate through the contact members. Therefore, the horizontal section is connected to the level of ground with a very low impedance. In this case, the rate of the unnecessary radiation attenuated by the horizontal section becomes high.
In addition to the above configuration, the contact members are provided in the vicinities of both ends of the horizontal section in a direction in parallel to the front panel.
Specifically, the top plate is electrically connected to the horizontal section, in a direction in parallel to the front panel, through the contact members provided in the vicinities of both ends of the horizontal section. The horizontal section is electrically connected to the bottom plate through the vertical sections provided at its both ends.
Therefore, the forward section of the top plate is electrically connected to the bottom plate with a value approximately equal to the impedance resulting from passing only the contact members and vertical sections. Thus, the impedance of the passage connecting the top plate and the bottom plate is very low. As a result, for example, when static electricity is applied to the top plate of the enclosure, it flows to the level of ground (chassis level) with a very low impedance.
In addition to the above configuration, the contact members are secured to the horizontal section by screws through upper supporting members provided at the front panel.
Namely, the upper side of the front panel is secured by the radiation shielding section.